Add Lightning Address support

This handles the LNURL-pay flow to enable Lightning Address support.
It accepts any lightning address name on your domain.

e.g. yourname@yourdomain.com

README.md

@@ -4,10 +4,10 @@ LnMe is a personal Bitcoin Lightning payment website and payment widget.
 
 ![demo](./lnme-demo.gif)
 
-It is a small service written in Go that connects to a [lnd node](https://github.com/lightningnetwork/lnd/blob/master/docs/INSTALL.md) and exposes a simple HTTP JSON API to create and monitor invoices. 
+It is a small service written in Go that connects to a [lnd node](https://github.com/lightningnetwork/lnd/blob/master/docs/INSTALL.md) and exposes a simple HTTP JSON API to create and monitor invoices.
 It comes with a configurable personal payment website and offers a JavaScript widget to integrate in existing websites.
 
-If [webln](https://github.com/wbobeirne/webln) is available the widget automatically use webln to request the payment; 
+If [webln](https://github.com/wbobeirne/webln) is available the widget automatically use webln to request the payment;
 otherwise an overlay will be shown with the payment request and a QR code.
 
 ## Motivation
@@ -19,7 +19,7 @@ BTCPay Server is too big and hard to run for that and I do not need most of its
 
 ## Installation
 
-LnMe connects to your [LND node](https://github.com/lightningnetwork/lnd/blob/master/docs/INSTALL.md), so a running LND node is required. 
+LnMe connects to your [LND node](https://github.com/lightningnetwork/lnd/blob/master/docs/INSTALL.md), so a running LND node is required.
 LnMe can easily run next to LND on the same system.
 
 1. Download the latest [release](https://github.com/bumi/lnme/releases)
@@ -55,6 +55,7 @@ Instead of the path to the macaroon and cert files you can also provide the hex
 * `static-path`: Path to a folder that you want to serve with LnMe (e.g. /home/bitcoin/lnme/website). Use this if you want to customize your ⚡website. default: disabled
 * `disable-website`: Disable the default LnMe website. Disable the website if you only want to embed the LnMe widget on your existing website.
 * `disable-cors`: Disable CORS headers. (default: false)
+* `disable-ln-address`: Disable [Lightning Address](https://lightningaddress.com/) handling.
 * `port`: Port to listen on. (default: 1323)
 * `request-limit`: Limit the allowed requests per second. (default: 5)
 
@@ -89,7 +90,7 @@ All environment variables must be prefixed by `LNME_` use `_` instead of `-`
 
 It is the easiest to run LnMe on the same node as LND. But you can run it anywhere as long as your LND node is accessible.
 
-#### Heroku 
+#### Heroku
 One click deployment with Heroku:
 
 [![Deploy on Heroku](https://www.herokucdn.com/deploy/button.svg)](https://heroku.com/deploy?template=https://github.com/bumi/lnme)
@@ -109,6 +110,16 @@ lnme.michaelbumann.com {
 `$ caddy  --config /etc/caddy/Caddyfile`
 
 
+### Lightning Address
+
+The Lightning Address is an Internet Identifier that allows anyone to send you Bitcoin over the Lightning Network.
+Lightning Address builds on [LNURL-pay](https://github.com/fiatjaf/lnurl-rfc/blob/luds/06.md) LnMe handles the necessary requests for you.
+
+For more information check out the website: [lightningaddress.com](https://lightningaddress.com/)
+
+Your Lightning Address: `{anything}@{your domain}`
+
+
 ### Customize your ⚡ website
 
 LnMe comes with a default website but you can easily configure and build your own using the the LnMe JavaScript widget or JSON API.

lnme.go

@@ -1,14 +1,19 @@
 package main
 
 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"flag"
+	"fmt"
 	"log"
 	"net/http"
 	"os"
+	"strconv"
 	"strings"
 
 	rice "github.com/GeertJohan/go.rice"
 	"github.com/bumi/lnme/ln"
+	"github.com/bumi/lnme/lnurl"
 	"github.com/didip/tollbooth/v6"
 	"github.com/didip/tollbooth/v6/limiter"
 	"github.com/knadh/koanf"
@@ -137,6 +142,45 @@ func main() {
 		return c.JSON(http.StatusOK, invoice)
 	})
 
+	if !cfg.Bool("disable-ln-address") {
+		e.GET("/.well-known/lnurlp/:name", func(c echo.Context) error {
+			name := c.Param("name")
+			lightningAddress := name + "@" + c.Request().Host
+			lnurlMetadata := "[\"text/identifier\", \"" + lightningAddress + "\"], [\"text/plain\", \"Sats for " + lightningAddress + "\"]"
+
+			if amount := c.QueryParam("amount"); amount == "" {
+				lnurlPayResponse1 := lnurl.LNURLPayResponse1{
+					LNURLResponse:   lnurl.LNURLResponse{Status: "OK"},
+					Callback:        fmt.Sprintf("%s://%s%s", c.Scheme(), c.Request().Host, c.Request().URL.Path),
+					MinSendable:     1000,
+					MaxSendable:     100000000,
+					EncodedMetadata: lnurlMetadata,
+					CommentAllowed:  0,
+					Tag:             "payRequest",
+				}
+				return c.JSON(http.StatusOK, lnurlPayResponse1)
+			} else {
+				stdOutLogger.Printf("New LightningAddress request amount: %s", amount)
+				msats, err := strconv.ParseInt(amount, 10, 64)
+				if err != nil || msats < 1000 {
+					return c.JSON(http.StatusOK, lnurl.LNURLErrorResponse{Status: "ERROR", Reason: "Invalid Amount"})
+				}
+				sats := msats / 1000 // we need sats
+				metadataHash := sha256.Sum256([]byte(lnurlMetadata))
+				memo := hex.EncodeToString(metadataHash[:])
+				invoice, err := lnClient.AddInvoice(sats, memo)
+				lnurlPayResponse2 := lnurl.LNURLPayResponse2{
+					LNURLResponse: lnurl.LNURLResponse{Status: "OK"},
+					PR:            invoice.PaymentRequest,
+					Routes:        make([][]lnurl.RouteInfo, 0),
+					Disposable:    false,
+					SuccessAction: &lnurl.SuccessAction{Tag: "message", Message: "Thanks, payment received!"},
+				}
+				return c.JSON(http.StatusOK, lnurlPayResponse2)
+			}
+		})
+	}
+
 	// Debug test endpoint
 	e.GET("/ping", func(c echo.Context) error {
 		return c.JSON(http.StatusOK, "pong")
@@ -157,6 +201,7 @@ func LoadConfig() *koanf.Koanf {
 	f.String("lnd-macaroon-path", "~/.lnd/data/chain/bitcoin/mainnet/invoice.macaroon", "Path to the LND macaroon file.")
 	f.String("lnd-cert-path", "~/.lnd/tls.cert", "Path to the LND tls.cert file.")
 	f.Bool("disable-website", false, "Disable default embedded website.")
+	f.Bool("disable-ln-address", false, "Disable Lightning Address handling")
 	f.Bool("disable-cors", false, "Disable CORS headers.")
 	f.Float64("request-limit", 5, "Request limit per second.")
 	f.String("static-path", "", "Path to a static assets directory.")

lnurl/types.go

@@ -0,0 +1,52 @@
+// THANKS: https://github.com/fiatjaf/go-lnurl/blob/d50a8e916232580895822178fe36e0f5cf400554/base.go
+// only using the LNURL types here
+package lnurl
+
+import "net/url"
+
+type LNURLResponse struct {
+	Status string `json:"status,omitempty"`
+	Reason string `json:"reason,omitempty"`
+}
+
+type LNURLPayResponse1 struct {
+	LNURLResponse
+	Callback        string   `json:"callback"`
+	CallbackURL     *url.URL `json:"-"`
+	Tag             string   `json:"tag"`
+	MaxSendable     int64    `json:"maxSendable"`
+	MinSendable     int64    `json:"minSendable"`
+	EncodedMetadata string   `json:"metadata"`
+	Metadata        Metadata `json:"-"`
+	CommentAllowed  int64    `json:"commentAllowed"`
+}
+
+type LNURLPayResponse2 struct {
+	LNURLResponse
+	SuccessAction *SuccessAction `json:"successAction"`
+	Routes        [][]RouteInfo  `json:"routes"`
+	PR            string         `json:"pr"`
+	Disposable    bool           `json:"disposable,omitempty"`
+}
+
+type RouteInfo struct {
+	NodeId        string `json:"nodeId"`
+	ChannelUpdate string `json:"channelUpdate"`
+}
+
+type SuccessAction struct {
+	Tag         string `json:"tag"`
+	Description string `json:"description,omitempty"`
+	URL         string `json:"url,omitempty"`
+	Message     string `json:"message,omitempty"`
+	Ciphertext  string `json:"ciphertext,omitempty"`
+	IV          string `json:"iv,omitempty"`
+}
+
+type LNURLErrorResponse struct {
+	Status string   `json:"status,omitempty"`
+	Reason string   `json:"reason,omitempty"`
+	URL    *url.URL `json:"-"`
+}
+
+type Metadata [][]string